My First-Ever QSO -- 50 Years After Passing Ham Test

Discussion in 'Ham Radio Discussions' started by G3EDM, Aug 27, 2021.

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  1. G3EDM

    G3EDM Ham Member QRZ Page

    I haven't and I know I should. It is a full-size dipole and almost a flat-top, centre-fed with 50-ohm coax.... It's cut for 7050.

    I've been doing half of that: I have been sending "? de G3EDM". Or sometimes just "?". Thanks for the explanation about QRZ?, I did know about that a long time ago but needed the reminder.

    73 de Martin, G3EDM
     
  2. G3EDM

    G3EDM Ham Member QRZ Page

    So, some more of those frustrating experiences where someone answers my CQ, then disappears after I answer their answer. But looking at the RBN, reports of my signal today vary from one minute to the next from 2 dB to 20 dB so this time I can definitely attribute this to "conditions on the band". Either I faded out completely at their end, or they faded out completely at my end, or both.

    Too bad, I almost added a couple of new countries there (Italy and Spain) and this time I was following the right procedure, copying their callsigns, and following up after the silent response with several X9XXX DE G3EDM KN in an effort to rescue the call.

    Generally this is encouraging!

    Edited to add: The "grey line" effect seems to be substantial, as far as local (European) propagation is concerned. The hour before and after daybreak is the best. Less so, for DX. Indeed I have hardly heard any DX on 40m for several days now.

    73 de Martin, G3EDM
     
    Last edited: Oct 22, 2021
  3. G3EDM

    G3EDM Ham Member QRZ Page

    You know there doesn't seem to be much wrong with that signal:

    [​IMG]

    With perserverance, and especially the replacement of the transmitter oscillator and tweaks to the antenna (including measuring the SWR) this ought to be pretty good. That's even before I build the new superhet receiver i.e. still within the constraints of kitchen-counter electronic building.

    73 de Martin, G3EDM
     
  4. W9BRD

    W9BRD Ham Member QRZ Page

    My test equipment currently consists of a DMM, a homemade reflectometer (G4ZNQ), a rectified-grid-voltage indicator, a power meter based on a diode peak detector, and an R&S NRA analog low power meter with a maximum full-scale range of 1 W. (When I worked at ARRL HQ, I did have access to a spectrum analyzer, HP signal gens, AF distortion analyzer, and other test/measurement goodies such that I was able to measure transmitter purity and receiver 3rd-order IMD DR and such, but that's a pleasant memory.)

    So nowadays I'm able to deduce the presence of such as VHF parasitics only indirectly. That's why, operating at "dc" in the "dc to daylight" scenario as I do at W9BRD, I -- for instance -- commonly add 10 pF directly to common from the plate-pin terminal of tuned-output stages, and, as Alan, W4AMV, described the general practice to me, "sprinkle lightly with R" in places where unwanted negative resistance may operate, such as "between plate and tuned circuit" and "in series with the plate or grid choke". Why should a stage I'm going to use at frequencies between 3.5 and 10.15 MHz be capable of any significant gain at all at VHF or LF?

    The patent officials who rejected Harold Black's negative-feedback application came by their disbelief honestly. Dating from the earliest days of ham-radio (and likely professional) tradition are such practices, driven by awful device capabilities and abetted esp in the Depression and postwar eras by the need to ruthlessly economize, as "low loss! low loss!", "operate every device at maximum ratings or higher", and "no neutralization required." Introduce intentional loss? Add components that don't have direct, measurable benefit now on gain and/or output? Build in neutralization and learn how to adjust it when a much simpler stage is "is stable as long as ___ and ___ and ___"? Inconceivable! What good is using an 807 if we don't operate it at -- at minimum -- 750 V and 100 mA plate? Not operating a device at maximum ratings or beyond is money left on the table, QSOs unachieved, awards absent from the wall.

    Enlightened RF savages like me can benefit from those with better skills, training, and test equipment by exactly such reports as Karl-Arne's. Ah, hysteresis in tuning -- that likely means trouble. (What Karl-Arne means there, grasshoppers, is that an output peak or current peak or dip does not occur in exactly the same control-range spot when we tune through it "from below" versus tuning through it "from above" -- a condition that when seen in an RF power amplifier may indicate that the stage is oscillating or at the edge of oscillation.") A "thickening of the trace"? Those with oscilloscopes -- which have specified high-frequency rolloff/response characteristics -- who might naturally expect significant operational flaws at harmonics and/or VHF/UHF can take such comments as training in the art of understanding that an "HF" scope only may give hints of gross misbehaviors well above their design high-frequency response. (We cannot reliably see harmonic energy many tens of dB down on a scope's display of a sinusoidal fundamental signal, for instance, even assuming that the harmonic we think we should be able to see is below the scope's high-frequency rolloff.)

    Another check we can do, especially useful if we've already noticed odd shifts or jumps in output or stage current when we expect smooth changes with tuning, is to carefully bring a large, insulated metal mass closer to the general wiring and/or tuned circuits of suspect stages to see if doing such causes further significant/sudden changes, including the appearance of frquency-shifting spurious signals as we monitor the fundamental signal, or even somewhat off the fundamental signal, in a nearby receiver. A stage oscillating at VHF or even HF may be far more sensitive to the proximity of lossy steel than it is when operating stably as an amplifier at its design frequency; a 12JQ6-based regenerative detector I once built that also oscillated at VHF could sense the presence of my hand a foot away. (And BTW, for a fun time, if you have an oscillator the inductor in which uses a ferromagnetic core, tune in its signal in a receiver with the BFO turned on and then slowly bring a permanent magnet closer to that equipment from, say, 3 feet away. At how far out does the pitch start noticeably shifting? Do you have a separate speaker anywhere near that oscillator? Try moving it farther away and see what happens. Now imagine what the line-frequency-varying magnetic field around nearby power transformers may be doing to the oscillator frequency. Pssst: I went to air-core coils from ferrous-cored coils in my homemade VFO as a result of investigating the real-world effects of this last thought experiment.)

    Ham radio as "big red schoolhouse" operates best when we realize that we're all still/always in school with respect to learning the science, art, and craft of working with and at RF.
     
    Last edited: Oct 22, 2021
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  5. W9BRD

    W9BRD Ham Member QRZ Page

    Correction: I left out the most important piece of test equipment: The most powerful computer known to exist in the universe.
     
  6. G3EDM

    G3EDM Ham Member QRZ Page

    This one arrived today:

    [​IMG]

    BTW the reason it says "Canterbury" (even though I don't live there) is that it is the nearest well-known city and is only about 10 miles (about 16km) away by road. So I always say "QTH NR CANTERBURY". Our village is actually much closer to a town called Ashford but almost no one outside the UK has heard of that....

    The QSL-card winners so far: France 2, Germany 2, Scotland 1. That is a bit unfair because I've only been on the air a couple of months so these are only the "direct mail" QSLs. The UK QSL bureau sends batches every three months and I haven't received any of those "bureau cards" yet.

    [​IMG]

    I QSL everyone direct, but that could get expensive if the QSO count finally starts to climb!

    I also QSL everyone via LOTW but so far only two of the 19 QSOs have responded there.

    73 de Martin, G3EDM
     
    Last edited: Oct 22, 2021
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  7. SM0AOM

    SM0AOM Ham Member QRZ Page

    I certainly can "chime in" on your views.

    Having learned basic electronics as a "resource-challenged" Grammar-School kid through the use of simple test gear; absorption wavemeters, home-made GDO, ancient VOM with diode probe, flashlight bulb with a small link, a "twin-lamp" matching indicator and later a "Mickey-Match" for indicating the presence of RF, made you rely on what could be deduced from observations. A general-coverage receiver also was a great assistance.

    Being "spoiled" at a more advance age by network and spectrum analysers, 400 MHz oscilloscopes,rubidium stabilised high-performance signal generators and such esoterica does not change the facts that a lot of RF phenomena are quite simple, and can be detected and evaluated by basic means, together with applications of very basic circuit theory and a dose of "common sense".

    I have been "industry advisor" in several MSEE thesis projects, and a quite common factor is that students sometimes over-complicate things.

    When your world-view is centered around differential equations and third-order effects even quite simple circuits may seem formidably complicated. When participating in "Systems Engineering" education projects I have sometimes met the objection "It has to be complicated...", not taking into account that most engineering problems may be handled using first-order approximations.

    I have reason to believe that the understanding and curing knowledge of vacuum-tube instability problems will vanish with our generation. Parasitic oscillations exist also in solid-state circuits, but have other causes and remedies, and in the "high-impedance world" of yesteryear they needed to be addressed in other ways.

    I have yet to meet an engineer or radio amateur aged 40 or younger that have fundamental knowledge about vacuum-tube circuits and who can explain the behaviour of unneutralised triodes taking the Miller effect into account. Already 40 years ago this was beginning to be a problem for the aerospace industry, as TWT:s still were used in EW and satellite systems.

    I took a course in "Microwave Amplifiers", where the lecturer was a section head at Ericsson Microwave who lamented: "Finding young engineers who can design vacuum-tube circuits is a major accomplishment, but finding one who can design the tube itself is like winning the lottery".

    We were only 8 students that showed up for the course "Engineering Electron Physics", and 10 were formally required for the course to be held, but Dr. Lundgren felt sorry for us and conducted the course anyway. Here, the "care and feeding" of electron tubes together with their internal design was covered, together with other valuable knowledge such as the inner workings of the reflex klystron and the Nyquist and Friis noise-figure models.

    Most of the course material was written in the 1960s by Professor Olof Rydbeck, astrophysics and radio astronomy pioneer and founder of the Onsala Space Observatory. It was no surprise that 2/3 of the students were radio amateurs and VHF:ers...

    Newly minted MSEE:s seldom even know about the existence of the great Georg Barkhausen.

    73/
    Karl-Arne
    SM0AOM
     
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  8. G3EDM

    G3EDM Ham Member QRZ Page

    One of my paternal great-uncles, Christopher Marris, was part of the team that helped develop the cavity magnetron in the late 30s and early 40s, leading directly to radar. Here's an excerpt from the memoirs of my grandfather Eric (George's brother) who was a civil servant:

    My brother Chris, head of the Radar research team at the G.E.C., the only team not incorporated in the official research unit from which Radar had sprung under Dr. Watson Watt, paid us many visits because he was working with the R.A.F. at Christchurch. He was the principal designer of the Magnetron valves made by Marconi-Osram for radar. The problem had been how to produce high powered electro-magnetic "blips", rather than low powered continuous waves, without burning up the valves. He took me over to Swanage for drinks at the hotel where all the official research people were concentrated. On a later occasion he arrived in a hurry saying he had to consult quickly one of his team who was on holiday at Bere in Devon, the place we had camped at with our four wheeler caravan in what seemed another life. He suggested I should go with him so we set off on a hair raising drive to Bere; for being blind in one eye he always drove on the wrong side of the road "to see better". Arrived at Bere we succeeded in finding the man's lodgings but he was said to be on the beach. No sign on the beach but at last we spotted a rowing boat far out at sea. We went out, in a hire boat and exchanged crews; Chris got in with his colleagues and the children got in with me. The conference at sea was only a few days before Chris himself installed the first ever radar in a plane. It was a night fighting Beauxfighter and in one of these my delightful assistant of the Munich days, Jack Reade, was killed.

    (Excerpt from the unpublished memoirs of Eric Marris)

    I must stress that I have not fact-checked this excerpt! I am sure that credit for radar was split an awful lot of ways....

    73 de Martin, G3EDM
     
  9. SM0AOM

    SM0AOM Ham Member QRZ Page

    Your ancestor seems to have been involved also in pre-cavity magnetron airborne intercept radar, which worked on VHF. Some pre-production units of the Airborne Interception RDF Mk III were installed in Bristol Blenheims and Beaufighters already in early-1940.

    Radar development was extremely rapid during 1940/41, and when the Tizard mission took the cavity magnetron design by Randall and Boot to the US, mass production of airborne microwave radar could begin.

    The "H2S" microwave radars that soon were installed in in night fighters for interception and in heavy bombers for ground mapping purposes were a major accomplishment.

    The history of radar and radio navigation is a fascinating subject, and I am currently writing a presentation about this subject for the 70 year jubilee of the Swedish Radio Navigation Board, of which I am a member.

    73/
    Karl-Arne
    SM0AOM
     
  10. G3EDM

    G3EDM Ham Member QRZ Page

    So this evening I tried a completely new tactic for scoring a QSO and ... it worked!

    You will recall that one of my biggest problems with the equipment, probably indeed the single biggest issue, is that a regenerative receiver -- while very sensitive -- has lousy selectivity. This means that much of the time, the ham bands just sound like a massive pileup because you could easily be hearing all of the signals from a 5 kHz-wide or 10 kHz-wide chunk of spectrum all at once.

    Here's what I did:
    • Pick out the loudest signal that is calling CQ.
    • Switch in massive attenuation on the receiver until that loud signal is just about the only signal you are hearing.
    • Then answer the CQ, choosing the crystal that is the closest in frequency to the "big gun" signal.
    • Do this over and over again in hopes that the other station will eventually hear you.
    Within about 15 minutes of trying this out, I had a QSO, and what's more, for once I could hear the other station loud and clear with (at least to start with) perfect clarity and no QRM.

    So that's a new country (Italy) and a good long distance: 923km (574 miles).

    This is my 20th QSO in two months on the air, and the very first time that I have successfully answered a CQ. It will be interesting to see whether my new tactic has further success! It certainly takes care of a large part of the "bad selectivity" problem, as long as the other station has a deafeningly strong signal (there are plenty of those, if you use a regen radio!).

    Here's what I had to do:
    • Turn the RF gain way down.
    • Rotate the antenna attenuator to maximum damping.
    • Completely de-tune the RF stage.
    • Adjust he regeneration throttle.
    Eventually ... about halfway through the QSO, even louder "big guns" became layered on top of his signal and he faded out, but came back in again. It was one of the most civilised QSOs so far because for most of it, I could hear him loud and clear and he seemed to be copying me fine. I gave him 599, he gave me 579.

    73 de Martin, G3EDM
     
    Last edited: Oct 22, 2021
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